Application stuck after bootloader start with WDT enabled

[gsalazar]

Hi,

I am using a custom board with the nrf52832 with SDK 13 and I have a bootloader and an application that both configure and feed the WDT.

However, upon restart (power off, followed by a power on) the application sometimes starts but gets stuck. This occurs at random instants and I see that the application starts with a LED right at the beginning of the code. However nothing else after that runs.

What might be causing this? I do need the WDT in the app and the bootloader to ensure that the MCU can recover properly

Thank you in advance.

[Sigurd]

Hi,

What WDT configuration are you using ? What behaviour and reload_value have you set?

Have you tried increasing the reload_value ?

[gsalazar]

Hi, 

I have the behaviour set as NRF_WDT_BEHAVIOUR_PAUSE_SLEEP_HALT and a reload time of 5 minutes.

Increase it to more than 5 minutes, I cannot really move it up due to the application that I have.

Thanks

[Sigurd]

Are you using DC/DC mode? Does the custom board have the DC/DC components, inductor L2 and L3?

[gsalazar]

I have both inductors with the same values and assembly as presented in the reference HW guide.

Do I need to explicitly enable the DC/DC mode?

[Sigurd]

If you have the inductors, then the DC/DC mode is not what is causing the issue. To answer your question; yes, you need to explicitly enable DC/DC mode. Use sd_power_dcdc_mode_set(NRF_POWER_DCDC_ENABLE) to enable it.

[gsalazar]

One thing I observed is that after the system hangs eventually the WDT triggers and the application boots correctly. I believe this means that the problem exists but the nrf52 is not completely blocked, just the application

[Sigurd]

It could be that the code somewhere tries to turn off the LF clock while the WDT is running, and therefore get stuck. But to figure out where in the code you are stuck, connect the debugger, and use “nrfjprog –readregs”. You will then need to take a look at the printed PC value to figure out where in the code you are. Use the PC value together with the .elf file and addr2line to find the file name and line number of where in the code you are. E.g.

addr2line -e filename.elf 0x23680

[gsalazar]

After doing what you described I see that I am stuck in the drivers_nrf/hal/nrf_clock.h file at line 356. This is the nrf_clock_lf_is_running function, however I never call this function nor any of the functions that call this one.

[Sigurd]

Are you sure that you are not calling nrf_drv_clock_uninit() , nrf_drv_clock_on_sd_disable() or nrf_drv_clock_lfclk_release() ?

This is SDK 13.1 ??

[gsalazar]

It is SDK 13.1,  I found a nrf_drv_clock_uninit() call buried in the code. I will try to test it without calling that function